已知2x*x+x-5=0,求代数式6x*x*x+7x*x-13x+11的值
问题描述:
已知2x*x+x-5=0,求代数式6x*x*x+7x*x-13x+11的值
答
6x^3+7x^2-13x+11
=6x^3+3x^2-15x+4x^2+2x-10+21
=3x(2x*x+x-5)+2(2x*x+x-5)+21
=3x*0+2*0+21
=21